When manufacturing hearing aid shells today typically audiologists produce a model of the shape of the individual auditory canals, thereby taking a mold thereof, typically of silicon. This model is then sent to the hearing aid manufacturer who on the basis of this basis casts a hearing aid shell from a plastic material.
This procedure is problematic under different aspects:
Based on the mold plastic materials must be used for the shell making, which result in a shell which is relatively hard and stable with respect to its shape. This as a result leads to the fact that when inserting the finished in-ear hearing aid into an individual's ear, on account of the remaining pressure spots, the shell of the hearing aid must practically always be refinished.
Even though the above procedure allows making the resulting relatively hard shell with an outer shape matching the mold, it does not allow making complex inner and/or outer shapes such as would be desirable for configuring in an optimal manner the shape of mounts for the hearing aid's functional components. We understand under the expression “functional components” all units which are provided for reception, processing and reproduction of audio signals, that is, microphones, digital processor units, loudspeakers and accessories such as remote controls, binaural signal transmissions, batteries, etc. It must additionally be borne in mind that optimal packaging of such functional components using the space available can only be realized on an individual basis, because the geometry of the auditory canal are substantially different from individual to individual.
The above-mentioned procedure is on one hand highly labor intensive and on the other hand the resulting hearing aid will mostly be less than optimal with respect to comfort of wear and space utilization. The material used in this conventional manufacturing furthermore necessitates a relatively thick wall of the in-ear hearing aid shell, thereby further and additionally reducing the space available for implementing the functional components.
The objective of the present invention is to eliminate these drawbacks. To that end the invention is characterized in that at least one shape of the application area for the device is three-dimensionally digitized to result in a set of data and that the ear device or its shell is realized by an additive built-up process controlled by the set of data. Even though this manufacturing method is particularly appropriate for in-ear hearing aids, it also may be used with comparable advantages for outside-the-ear hearing aids, further for other ear devices, as e.g. for manufacturing earphones of all kinds, water-protection inserts, noise-protection inserts etc. In a preferred embodiment of the method according to the present invention account is taken that the area where the ear device is applied to the individual—think in particular of in-ear ear devices—undergoes a substantial dynamic in everyday life, for instance the auditory canal during chewing. By registering a single shape of the area of application of the device, so to speak as a snapshot, such dynamics cannot be taken into account for manufacturing the ear device. According to a preferred embodiment of the method according to the present invention, it registers more than one shape of the individual area of application of the device during its natural motion or at distinct positions out of that natural motion similarly to registering a movie of the dynamics of the application area, and it controls the additive built-up process in function of the data set so obtained.